ciliates, and flagellates within a crystalline scaffolding. Other organisms are caught up in brash-ice slush and frazil-ice clumps that are incorporated into the larger floe. Thus there is a surface snow-biota and a subsurface ice-biota. There are ample nutrients for each. Nitrates and phosphates gravitate to the lower strata of floes, where biological productivity is greatest, and microalgae migrate along capillaries and through brine channels within the floe—weakening the structural strength of the floe and tinging the floe with a brownish stain. Incredibly, the density of microalgae populations and the productivity of the ice biota are perhaps greater than in seawater. An ice fauna, in turn, grazes on this ice flora. Ice biotas contribute as much as 20 percent of the total primary production of Southern Ocean biomass. Whether or not the nutrients and biota released by the recession of the pack actually “seed” the phytoplankton bloom that occurs at the same time is undetermined, but this bloom contributes significantly to the seasonal cycle of life.
The trophic hierarchy of Antarctica is comparatively simple. The food chain is characterized by large numbers of a few species, an enormous biomass within a less diverse ecosystem than those typical of temperate or tropic lands. Virtually all of its bird biomass (99 percent) consists of penguins, and they are dominated by one species, the Adelie. Nearly three-fourths of all Antarctic fishes belong to one group, the nototheniformes. The crabeater seal is the most abundant seal in the world; this single species accounts for 85 percent of Antarctic pinnipeds. The baleen whale dominates the Antarctic whale population, the greatest herd in the world ocean. The impressive yields are best explained by an abbreviated food chain. Even compared to the Arctic—with its biotic connections to the land masses of Asia, Europe, and North America—the Antarctic is almost artlessly uncomplicated. The marine ecosystem thus mimics The Ice: great bulk in an equally awesome simplicity. Among the advantages enjoyed by this marine ecosystem, it should be noted that sea temperatures remain relatively constant and that the main seasonal change is restricted to the oscillation of the pack. The tremendous seasonal fluctuations in sunlight and ice cover, however, are vital for controlling the variable productivity of the system. Continental influences act indirectly on the biota through their control over pack ice production.
Phytoplankton consist principally of diatoms and dinoflagellates. Their abundance is legendary. The figures may be exaggerated, but the primary productivity of the system is often estimated to be the richest in the world ocean, perhaps four times greater than anywhere else. Primary production is greatest along the coastal areas, excluding the nearshore environments that are scoured or coated by ice, and amid the coastal seas, the deep embayments that surround West Antarctica. The nutrient-rich cold broth that upwells from the circumpolar deep water, along with possible contributions of phosphate or other minerals from discharged icebergs, accounts for much of this abundance. Accordingly, productivity is most prominent just below the cold surface waters that veneer the nearshore drift, and it shows pronounced geographic and seasonal variations.
But it is the next trophic layer that provides a universal link in the food chain. The euphausiid shrimp known as krill is the only significant connection between the primary producers and all the higher trophic feeders. Like the phytoplankton on which it grazes, krill converges around the Antarctic Peninsula; the Scotia Sea, nourished by the cold waters of the Weddell Sea, is especially favored. But the importance of krill to the circumpolar ecosystem depends also on its mobility. It is found everywhere around the continent, though the heaviest concentrations of Euphasia superba are embedded within the east wind drift of the Antarctic circumpolar current. Krill feeds by migrating in a daily rhythm vertically through the water column, exploiting the upward leaching of nutrients, and it migrates around the continent in vast surface or near-surface swarms, with tons of krill to a swarm. Because of its universal importance, directly or indirectly, to all subsequent trophic levels, krill establishes the basic geography and dynamics of biology in the Antarctic. Life is pelagic, migratory, seasonal, abundant in mass and scanty in variety.
On the krill swarms feed squid and fish; on them feed other fish, birds, and mammals. Although relatively constant in its temperature, the Southern Ocean is bitterly cold. Cold-blooded species, such as fish, adapt by several means to temperatures that would otherwise freeze internal fluids, including the production of several chemical antifreezes that swirl through their body fluids. Warm-blooded species acquire insulating layers, such as blubber or down, by which to retain heat. Virtually all Antarctic birds are pelagic. Some, like the albatross, live and breed outside the pack; others, like penguins, live on the pack; a few, like skuas and penguins, reside at least seasonally along the coastline. But, apart from its penguins—eleven of the eighteen species are present—Antarctica is best known for its marine mammals. There is a fur seal that inhabits subpolar islands and there are true seals—the leopard, crabeater, Weddell, Ross, and elephant—that thrive on the pack. There is a porpoise, the killer whale. And, of course, there are the famed true whales. Whales migrate to the Antarctic during the austral summer, but their abundance is (or was) astonishing. The presence of fur seals and whales first drew humans to the south polar regions.
Humans, of course, are the great anomaly in the Antarctic ecosystem. In some respects—notably their migratory and seasonal habits—they resemble typical Antarctic organisms. But in other ways they are ill-adapted aliens who find the Antarctic as disruptive as the Antarctic biota finds them. They arrived on the continent only in the twentieth century, and they have never become an integral part of the marine ecosystem. They extract from the system, removing organisms to take back to civilization, but they never contribute to the ecosystem’s productivity. Their best adaptations are simply to limit the amount they take from the system, or to substitute for the higher trophic feeders, such as whales, whose numbers they have reduced. It is not that humans cannot cope with polar environments; they have adapted famously to the Arctic. Rather, the peculiar isolation and reductionism of The Ice render its occupation problematical for humans. In coping with The Ice, humans must overcome not only the energy gradient, with its abstraction of accessible food and water, but the information gradient, which strips the region of meaning. By its nature the polar vortex repulses rather than beckons. It drains rather than contributes. By its awesome simplicity The Ice becomes exclusive.
Yet humans have one singular achievement: they have bound the marine ecosystem to those terrestrial ecosystems which humans inhabit elsewhere and, through them, have begun the biotic occupation of the Antarctic continent. No other organism systematically lives on the interior ice sheets. It is precisely because humans need not live off the ice, however, that they can live on it, that they alone have crossed the biotic boundary shielding the lifeless Ice from the living Earth. For the most part, inland from the coastline biological complexity in the Antarctic ceases. It is the peculiar burden and desire of humans—those from certain civilizations—to extend that complexity inward. It is a complexity of information, not merely of ecology. It is not what they find in Antarctica that sustains these humans but what they bring to it and surrender to The Ice.
A Kinetic Art: The Esthetics of the Pack
The pack marks an esthetic no less than a geographic border. In its light, colors, shapes, and motions, the pack defines the ragged transition from landscape to icescape, from Earth art to Ice art. Because it is a vast zone of mixing, the pack is the most active and variously populated ice terrane; the site of the most striking contrasts of sky, sea, light, shape, motion, and ice; the region richest in sensory data, information, and perspectives. Of all the terranes within the Antarctic ice field, the pack is the most complex. It is no accident that so many artists who come to Antarctica confine themselves to the pack, where access is easiest, where life is abundant and exotic, where light effects are varied and subtle, where (if near the coast) mountainous backdrops offer traditional perspective and a reassuring allusion to alpine esthetics.
Much of the variety results from seasonal changes. During midsummer, after the pack has rapidly disintegrated and the fog that normally shadows it has vanished, something resembling a modified seascape is possible. Sunlight plays with storm cloud to illuminate a silver-grey sea, dappled with ripples and swells, ice flakes and floes. The sky is colored with subdued pastels of yellow, grey, and blue, mixed with grey and white cloud. In the distance, bounded by the pack, the horizon is obliterated
